High-efficiency discharge-device system



Dec. 11,1928.

J. L. FEARING HIGH EFFICIENCY DISCHARGE DEVICE SYSTEM wry/W Filed Aug. 15, 1923 Patented Dec. 11, 1928.

UNITED STATES PATENT OFFICE.

JUSTIN L. FEARING, OF JAMAICA, NEW YORK, ASSIGNOR TO WESTERN ELECTRTC COM- PANY, INCORPORATED, OF NE YORK, N. Y., A CORPORATION OF NEW YORK.

HIGH-EFFICIENCY DISCHARGE-DEVICE SYSTEM.

Application filed August 15, 1923. Serial No. 657,484.

This invention relates to discharge device systems for efiicient production and amplification of electrical waves. A general principle made use of in carrying out the invention is that of controlling the impedance of a discharge device by means of a grid or other control element whereby energy losses resulting from undesired passage of current through the device are reduced.

An object of the invention is to improve the operating etliciency of impulsively or shock excited amplification or other discharge device systems. i

A further object is to prevent energy losses in impulsively excited discharge device systems by preventing current from flowing in a reverse direction through the discharge de' vice during those periods when no impulses are impressed and consequently when current flow should not occur.

A further object is to provide more elficient modes of producing high power carrier waves for radio transmission and more efficient modes of amplifying carrier waves.

In a particular system embodying the invention, a source of waves is connected to the grid-filament circuit of a vacuum tube repcatcr which is provided with a sufiiciently negative grid potential so that only the peaks of the impressed waves result in a space current flow in the anode-cathode circuit of the tube. l/Vhen current is flowing through the tube. energy is stored in an inductance in the anode-cathode or plate circuit. At the end of each energy storing period, the inductance discharges through a rectifying device in the form of a short im ulse which excites a tuned circuit. 'The rectifying device is provided with a grid which is coupled tothe inductance of the tuned circuit in such a manner that the grid becomes positive at the time when discharges occur and negative during that portion of the cycle of oscillation of the tuned circuit when no discharges occur. This prevents current fiowing backward through the rectifying device during each alternate half cvcle.

The novel features which are believed tobe characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to particular embodiments thereof and its mode of operation will be best understood by reference to the following description taken in connection with the accompan ing drawings in which Fig. 1 represents a high efiiciency radio transmission system operating on the shock excitation principle; F1 1" is a modification thereof in which a p ase shifter is made use of for regulating the impedance of the high power discharge device; Fi 1", a modification in which current flow t rough the device in the wrong direction is immediately checked by reaction of the tube upon its own grid circuit; Fig. 2 is a diagram referred to hereinafter in explaining the operation of Figs. 1, 1 and 1"; Fig. 3, a system in which two tubes each operate to handle impulses of more than one polarity of an impressed wave; Fig. 4, a system in which a rectifying device is provided to negatively polarize the grid of a re eater tube in order to prevent energy losses ue to undesired current flow therethrough; Fig. 5 is a voltage diagram referred to hereinafter in explaining the operation of Fig. 4; Fig. 6 is a system combining certain features of Figs. 1 and 3; and Fig. 7 is an amplifier system in which several stages of push-pull amplifiers are used to impress large power on the output circuit.

In this specification, the expressions grid circuit and plate circuit will be employed with the significance of grid-cathode circuit .and anode-cathode circuit respectively.

Fig. 1 represents a system for impressing high power waves upon a radiating antenna 1 from a relatively low power source 2. Source 2 may have a frequency equal to the frequency of the waves to be radiated or a sub-multiple thereof. Although the waves from source 2 may have any form they preferably, on account of considerations of efficiency, are flat-topped, consisting of positive impulses or both positive and negative impulses. The source 2 is connected to the grid circuit of a vacuum tube am lifier discharge device 3 in series with con ensers 4 and 5 which are preferably of adjustable capacity. The grid is made normally negative by a source 6 connected in series with resistance 7. The grid is preferably adjusted to such a negative Value that space current does not flow in the plate circuit due to the voltage maintained in this circuit.

impressed on the anode circuit through coil 8 from the anode potential source, current only flowing when the applied potential from the source 2 reduces the negative grid voltage sufficiently to allow current to flow. The grid may have any negative value from that at which space current is normally just prevented from flowing in response to the potential applied to the anode of tube 3 through coil 8 from the s ace current source of tube 3 to that at whic only the extreme peaks of the waves supplied from the source 2 result in any space current flow. The value of the potential of source 6 is not critical and may have a range of values. However, potential applied to the grid by source 6 through resistance 7 must necessarily be such that the grid voltage is at times reduced to the point where current will flow in the anode circuit of device 3. A coil 8 of high inductance is connected in the plate circuit of the tube 3.

In parallel with the coil 8 is the anode-cathode path of a tube 9 and a loop resonant circuit consisting of condenser 10 and coil 11 which are adjusted to approximate resonance at frequencies of waves to be produced. A coil 12 is coupled to the coil 11. The coil 12 is included in the grid circuit of the device 9. The antenna circuit 1 is variably coupled to the coil 11 by coil 11 or any other suitable coupling.

The operation of the system of Fig. 1 is as follows: Positive impulses from source 2 render the grid of the tube 3 more positive or less negative so that space current tends to flow therethrough, and preferably give the grid such a potential that the impedance of tube 3 is a minimum, the duration of the flattopped impulse being varied if desired in accordance with some signal which it is desired to transmit. During the time the space current path is conductive the plate circuit battery of the device 3 tends to set up a constantly increasing flow through the coil 8. When the grid of the tube 3 again becomes so negative that the tube 3 is of high impedance, the energy stored in the coil 8 causes a sudden discharge of current through tube 9. If the source 2 supplies waves of uniform amplitude and constant frequency, there will be a succession of discharges through the tube 9 represented by the impulses 13, 13 of Fig. 2. If

these impulses occur with a periodicity cor responding to the natural frequency of the circuit 10, 11, oscillations will be set up and The current of each impulse will be so timed as to add to the charge of the condenser 10 at about the time when it is fully charged, the condenser electrode connected to the filament being at this time positive. Between impulses, the condenser discharges through the coil 11 so as to execute oscillations. During each oscillation, the electrode of the condenser adjacent the filament becomes negative which results in a tendency for current to be discharged through the tube 9. If this discharge were allowed to occur, a considerable portion of the'energy supplied to the circuit 10, 11 during one part of its cycle would be lost during the other part of its cycle. However, this is prevented by connecting the grid of tube when the inductance 8 discharges through the tube 9. 'The oscillatory energy set up in the circuit 10, 11- is transferred into the antenna circuit 1 and radiated.

Fig. 1 is a modified form of that part of the circuit of Fig. 1 to the right of the dotted line X-X. In this arrangement, a phase shifter 13 whichmay be of any suitable form, one form being illustrated in the patent to Englund reissue 15,089, April 19, 1921, is placed in circuit with the coil 12 so that the phase of'the potential on the grid of the tube 9 may be regulated either forward or backward as may be desired in order to bring it to the phase relation best suited for operation.

Fig. 1" represents another modification of that portion of the circuit of Fig. 1 to the right of the line XX. In this arrangement, a high resistance 14 is connected in series with other elements across the anode-cathode terminals of the tube 9. In series with the resistance 14 is a condenser 15. The grid of the tube 9 is connected by a variable tap connection to the resistance 14 and a grid polarizing battery 16 is connected in the grid circuit. The condenser 10 and the coil 11 are connected in the plate circuit adjacent the anode and a load or work circuit 17 is'coupled to circuit 10, 11.in any suitable manner but preferably by means of a coil 18 coupled to the coil 11.

The operation of the circuit of Fig. 1 is as follows: When a large current is flowing through the coil 8 and the impedance of the tubej3 suddenly becomes large, the coil 8 discharges an impulse through the circuit of the condenser 15 and resistance 14. Thegrid of the tube '9 becomes considerably less negative or more positive as a result of this cur rent flow thereby-greatl reducing the impedance of the tube 9 an the greater part of the energy stored in the coil 8 is discharged through the tube-9 thereby setting up oscillations in the circuit 10, 11. When the circuit 10, 11 is oscillating and the anode of tube 9 becomes positive thereby tending to Cause current flow through the tube 9, any smallcurrent which flows renders the grid of the tube 9 more negative because most of the current flowing through the tube 9 passes through the resistance 14 due to the relatively high impedance to short impulses of i1 8 as compared to the impedance of resi nce 14 in series with condenser 15. If desired battery 16 may make the grid of tube 9 normally so negative that the maximum voltage set up in the oscillatory circuit 10, 11 cannot cause current to flow back through the tube 9,

In Fig. 3, the grids of amplifier tubes 20 and 21 are polarized so negatively by sources 20? and 21 respectively that normally, space current is just on the verge of passing through the tubes when no impulses are being received from source 2. The tube 20 repeats impulses of one polarity from the source 2 and the tube 21 repeats impulses of the opposite polarity. The resistance corresponding to the resistance 7 of Fig. 1 is omitted but may be included if desired. When the tube 20 becomes of low impedance due to the applied potential of source 2, current flows in a circuit includin the battery 22, tube 23, coil 24, coil and tu%e 20. When the tube 21 is of low impedance, current flows in the circuit including the battery 26, tube 27, coil 24, coil 29, and tube 21. For the purpose of tracing the operation of tubes 20, 21, the circuit may be looked upon as though tubes 23 and 27 were omitted, that is, short cireuited for example, and coils 25 and 29 omitted from the circuit and the resulting breaks closed. Current passing through tube 20 tends to pass also through tube 21 because of the voltage across coil 24 being added to the voltage of battery 26 and the negative grid polarizing source 21 for the tube 21 being insuificient to prevent the flow of space current when the voltage of battery 26 is supplemented by the voltage across coil 24. One advantage in adjusting the potentials of polarizing sources 20' and 21, as described, is that these tubes ma be operated by waves of smaller amplitude rom the source 2, and the wave form of the com bined wave produced by tubes 20, 21 more nearly corresponds to that from the source 2. When current passes through tube 21, there is a tendency, similar to that described above, for energy being transmitted to coil 24 to be lost by discharge through tube 20.

Tubes 23 and 27 together with their connected circuits are provided to prevent the loss of energy caused by the above described flow of current from coil 24 through the out put circuit of the other tube. The grids of tubes 23 and 27 are normally polarized negatively. When current is transmitted tocoil 24 from tube 20 in response to a wave from source 2, the voltage occurring across coil 25 applies such a negative charge to the grid of tube 27 that space current cannot flow through tubes 21 and 27. At the same time coil 29 has induced therein a voltage which transmits a positive charge to the grid of tube 23 to render the tube of low or minimum impedance.

When current is transmitted to coil 24 from .tube 21, the voltage across coil 29 applies such a negative charge to the grid of tube 23 that space current cannot flow through tubes 20 and 23. At the same time coil 25 transmits a positive charge to the grid of tube 27 to render the tube of low or minimum impedance. A variable condenser 30 may be and preferably is connected across the coil 24 and adjusted to resonance with the "waves which are to be produced. An out ut circuit 31 is coupled to the system of coi 25, 24 and 29.

In Fi 4, waves from source 2 are impressed t rough transformer 32 upon two rectifiers 33 and 34 which are connected in parallel across the secondary of transformer 32 and are poled in opposite relation with respect thereto. When impulses of current pass through the rectifier 33, a sharp positive, followed by a sharp negative impulse will be produced in the secondary winding of the variable coupling transformer 35. The steepness of the sides ofthese impulses is controlled by varying the potential of source 33 poled to oppose space current through tube 33. The amplitude of the impulses may be adjusted by varying the coupling of transformer 35. The ositive impulse will be transmitted to an im ressed upon the grid of power amplifier tube 36. The negative impulse impressed upon the grid of the tube 36 will not produce any result but the positive impulse will cause a corresponding impulse of space current to pass in the plate circuit of tube 36 thereby charging up the condenser'lO and causing it to oscillate in conjunction with the coil 11. A rectifier 38 connected across the secondary winding of the transformer has for its sole function to limit the value of positive impulses impressed upon the grid of the tube 36, the source of potential in series with tube 38 being poled to oppose space current therethrough and of such value as to shunt away from the grid of tube 36 positive potentials in excess of that which renders tube 36 of minimum impedance. During those half cycles when no current is passing through t e tube 33, current passes through the rectifier tube 34 and the resistance 39. The resist-- ance 39 is connected in a circuit connecting the grid and the cathode of the tube 36 and consequently, current flow through the resistance 39 tends to make the grid of the tube 36 more negative. This results, therefore, in increasing the impedance of the tube 36 during those half cycles of oscillation of circuit 10, 11 when the tube 36 would tend to dissipate the energy stored in the circuit 10, 11.

Fig. 5 illustrates the voltages applied to certain elements of the circuit of Fig. 4 dur-. ing the cycle of operation. The sharp positive and negative impulses 40 and 41 reprelZh sent the voltages set up across the secondary through resistance 39. It obviously appears that the grid of the tube 36 is made negative in accordance with the curve of potential 45 during that portion ofthecy'cle of oscillaation of the circuit 10, 11 when the anode of the tube 36 is most positive as a result of the sum of, the oscillating voltage across condenser l0 and the voltage 'o f'source 36. Ourrent consequently tends to flow through the tube 36 from the anode to the cathode. The effect of wave 45 upon the grid of tube 36 is to prevent the discharge of energy from oscillatory circuit 10, 11 through tube 36. In view of the very steep sides of the "impulses 40 which cause space current impulses to be transmitted to circuit 10, 11 the very low impedance of tube 36 when conducting, and the very low impedance of condenser 10 to harmonies of the wave to which circuit 10, 11 is tuned, the fundamental wave is produced at very high elliciency. It is to be understood that this fundamental wave may actually be a band of waves of radio or carrier wave frequency, as for example, a single side band of a speech modulated carrier Wave impressed by the source 2. If desired the circuit containing tube 38 between the grid and cathode of tube 36 may be omitted.

In 6, waves from a source 2 are impressed upon the input circuits of two amplitier systems each consisting of a number of tubes in tandem. The tubes 46, 47 and 48 repeat impulses of one polarity and the tubes 49, 50 and 51 repeat impulses of the other polarity. Each tube 46, 47, 48, 49, 50 and 51 has applied to its grid such a negative polarizing potential as to be normally blocked and pass no space current. Alternate tubes in each series, as for example, the tubes 47 and 50, have their input and output connections reversed with respect to the adjacent tubes so that, with the illustrated positioning of the grid biasing andspace current batteries, a potential applied to the input circuit of the first tube of eachseries causes-a s ace current flow in the second tube and this in turn a space current flow. throuh the third tube. Impulses supplied to the inputcircuit of tube 46, for example, ap ear in amplified form in the plate circuit 0% the tube 48 and impulses applied to the grid circuit of the tube 49 appear in amplified form in the plate circuit of the tube 51. Each of the'tubes 48 and 51 has its plate circuit connected through 'tube is operating an a load circuit 52 conventionally indicated as consisting of an inductance and capacity in parallel. Each of the tubes 48 and 51 is also provided with a resistance common to its own plate circuit and the grid circuit of the other tube whereby each tube is rendered inoperative and of high im edance when the other is of low im edancer For example, current flowing in t e plate circuit of the tube 48 passes through the resistance 53 which impresses a negative potential upon the grid of the tube 51 and current flowing in t e plate circuit of the tube 51 asses through t e resistance 54 in such a direction as to im ress a. negative potential upon the grid 0% the tube 48. The circuit arrangement of Fig. 6 constitutes an am lifier circuit of general application of which the operation is sufiiciently obvious from the preceding description as to need no detailed explanation.

Fig. 7 represents an amplifier system in which waves from a source 2 are to be impressed upon a load circuit 55 to which is to be supplied considerable power. Several stages of amplification are provided each consisting of two tubes in push-pull relation, the stages being coupled to each other by means of conductive couplings including a high resistance element common to the late circuit of each tube and the grid circu t of the next tube in tandem. The output circuits of the last stage include tuned circuits 58 and 59 which are coupled to the antenna or load circuit 55. The alternate tubes, preferably the first and third, have grids nor mally negatively polarized to such an extent that-space current does not flow and the remaining tubes, preferably the second tubes 56 and 57 of each series, have grids normally positively polarized to such an extent that the normal space current is approximately the saturation current which cannot be sub stantially increased.

In operation, each series of tubes shown in Fig. 7 repeats and amplifies impulses of one sign supplied from source 2. Thus a positive impulse applied to the grid of the first tube causes an impulse of space current through the resistance in the plate circuit. This decreases the potential of the tube 56, for example, to-such an extent as to cause a decrease in the space current flowing therethrough which in turn raises the potential of I the third tube of the series and allows space current to flow. Consequently, of the tubes in each series, space current will be flowing in the alternate members only at one particular instant of time. If it is desired to amplify only impulses of one sign supplied from the source 2, the circuit arrangement of Fig. 7 may be modified by omitting one series of tubes.

All sources of voltage, resistances, capacities, inductances and impedance elements are to be understood as adjustable in magnitude whether so indicated on the drawing or not.

Having described several embodiments of the invention, the parts, features, combinations and methods which are believed to be novel and patentable are set forth in the appended claims.

What is claimed is:

1. The method of rectifying periodically repeated impulses to produce oscillations by means of a rectifying device, which comprises applying current impulses to the rectifying device, causing the impulses to set up oscillations having a frequency integrally related to the impulse frequency and causing the oscillations to control the impedance of the rectifying device whereby its im edance is increased to a high value during e interval between successive impulses.

2. In an impulse excited discharge device system, a space discharge device, a source of periodic impulses, means for impressing impulses from said source on said space discharge device to produce impulsive space discharges therein, and additional means controlled by the' action of the impulsive discharges to prevent the passage of current through said discharge device in the intervals between successive impressed impulses.

3. An amplifier having an input circuit, containing a source of pulsating current, an output circuit for said amplifier containing an inductance element, means for exciting said amplifier from said source to cause it to impulsively transmit energy to said inductance element whereby a reverse voltage is produced by said inductance during the period between impulses, and means associated with said amplifier for periodically raising the impedance'of said amplifier during the periods when said reverse voltages are applied in order to prevent loss of energy from said output circuit.

4. A wave repeater which comprises an electron discharge device, an input circuit containing an impulse enerator for suppl; ing periodic impulses thereto, an output circuit tuned to a frequency integrally related to the impulse frequency, control means for controlling the impedance of said device, and means coupled to said output circuit for impressing waves produced by the impulsive excitation thereof upon said control means to make said device of high impr dance during the interval between successive impulses.

5. A system comprising a space discharge device, a source for supplying a periodic succession of impulses thereto, a tuned circuit in series with said space discharge device, impedance controlling means for said space discharge device, and means electrically related to said tuned circuit for impressing waves produced by the impulsive excitation thereof upon said impedance controlling mea' 18 to increase the impedance of said device during the interval between successive impulses.

6. In combination a source of electrical impulses, a discharge device operated by im; pulses of positive sign from said source, another discharge device operated by impulses of negative sign from said source, and means whereby each of said devices renders the other of high impedance when said each device is energized by an impulse of current.

7. A source of waves to beam lified, a series of discharge, devices for amp ifying positive impulses thereof, a series of discharge devices for amplifying negative impulses thereof, each of said series of devices being provided with a negative grid polarizing voltage of suflicient value to produce a normally blocked or no space current condition when no waves are being supplied from said source.

8. A system of space dischar e devices each having plate and grid circuits or amplifyin electrical waves, said devices being arrange in a series in tandem relation, and means for applying negative grid voltages to the alternate members of said tandem series whereby they have normally zero s ace current.

9. A method of roducmg oscillations in an oscillating circuit by means of a variable impedance rectifier and an inductance, which comprises appl ing pulsating current to the variable impe ance rectifier, allowing pulsations of one polarity to flow through the inductance, increasing the impedance of said rectifier to prevent pulsations of the opposite polarity from flowing therethrou h, causing said inductance to set up oscil ations and preventing the energy of said oscillations being withdrawn from said oscillating circuit through an .energy dissipating pat including said rectifier.

10. A repeating system eomprisin a unidirectionally conducting dischar e (fBVlCG, a source of impulses separate there rom, means to impress impulses from said source on said device, a tuned circuit in circuit with said device to be excited into oscillation by current flowing as a result of said impulses, and means for cyclically rendering said device of high impedance in such phase relation with respect to the oscillations in said tuned circuit as to prevent dissipation of the energy in said circuit in said device.

11. A system of space discharge devices each having plate and grid circuits for amplifying electrical waves, said devices being arranged in a series in tandem relation, and means for applyin negative grid voltages to the alternate mem ers of sai tandem series whereby they have normally zero space current.

12. A system of space discharge devices, each having an anode, a cathode, and a grid, circuits connecting said devices in tandem relation, said circuits including series connections between the cathodes and the grids of adjacent tubes and grid polarizing sources for producing normally zero space current in at least two of said devices.

13. A system of space discharge devices circuits including series connections between 1 the cathodes and the grids of adjacent tubes, each of said impedance controlling elements having normally such a condition as to produce small energy loss within the device by making the current flow. small.

In witness whereof, I hereunto subscribe my name this 11th day of August, A, D. 1923.

JUSTIN L. FEARING. 

